/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
/*=========================================================================
 *
 *  Portions of this file are subject to the VTK Toolkit Version 3 copyright.
 *
 *  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
 *
 *  For complete copyright, license and disclaimer of warranty information
 *  please refer to the NOTICE file at the top of the ITK source tree.
 *
 *=========================================================================*/
#ifndef itkExtractImageFilterRegionCopier_h
#define itkExtractImageFilterRegionCopier_h

#include "itkImageToImageFilterDetail.h"

namespace itk::ImageToImageFilterDetail
{
/**
 *  Call the base class version: ImageToImageFilterDefaultCopyRegion
 */
template <unsigned int T1, unsigned int T2>
void
ExtractImageFilterCopyRegion(
  const typename BinaryUnsignedIntDispatch<T1, T2>::FirstEqualsSecondType & firstEqualsSecond,
  ImageRegion<T1> &                                                         destRegion,
  const ImageRegion<T2> &                                                   srcRegion,
  const ImageRegion<T1> &)
{
  ImageToImageFilterDefaultCopyRegion<T1, T2>(firstEqualsSecond, destRegion, srcRegion);
}

/**
 *  Call the base class version: ImageToImageFilterDefaultCopyRegion
 */
template <unsigned int T1, unsigned int T2>
void
ExtractImageFilterCopyRegion(
  const typename BinaryUnsignedIntDispatch<T1, T2>::FirstLessThanSecondType & firstLessThanSecond,
  ImageRegion<T1> &                                                           destRegion,
  const ImageRegion<T2> &                                                     srcRegion,
  const ImageRegion<T1> &                                                     itkNotUsed(totalInputExtractionRegion))
{
  ImageToImageFilterDefaultCopyRegion<T1, T2>(firstLessThanSecond, destRegion, srcRegion);
}

/**
 * Copy an image region (start index and size) for the case where
 * the source region has a lesser dimension than the destination
 * region.  This version is "smart" in that it looks at what
 * dimensions should be collapsed.  This information is passed in
 * the parameter totalInputExtractionRegion.  Any values within
 * totalInputExtractionRegion.Size that are zero correspond to the
 * dimension to be collapsed.
 *
 * Note that the use of source and destination reflect where
 * where is information is coming from and going to.  When used
 * in the pipeline mechanism, the region requested by the output
 * of a filter is used to define the region required on the input.
 * In this case the output of the filter is the source and the
 * input of the filter is the destination.
 */
template <unsigned int T1, unsigned int T2>
void
ExtractImageFilterCopyRegion(const typename BinaryUnsignedIntDispatch<T1, T2>::FirstGreaterThanSecondType &,
                             ImageRegion<T1> &       destRegion,
                             const ImageRegion<T2> & srcRegion,
                             const ImageRegion<T1> & totalInputExtractionRegion)
{
  // Source dimension is less than the destination dimension, so look
  // at the m_TotalExtractionRegion and see what values in size are 0.
  // With these values, lock the destRegion.Index to the corresponding index


  Index<T1>         destIndex;
  Size<T1>          destSize;
  const Index<T2> & srcIndex = srcRegion.GetIndex();
  const Size<T2> &  srcSize = srcRegion.GetSize();
  int               count = 0;
  for (unsigned int dim = 0; dim < T1; ++dim)
  {
    // for dimensions to be removed
    if (!totalInputExtractionRegion.GetSize()[dim])
    {
      destIndex[dim] = totalInputExtractionRegion.GetIndex()[dim];
      destSize[dim] = 1;
    }
    // for all other dimension
    else
    {
      destIndex[dim] = srcIndex[count];
      destSize[dim] = srcSize[count];
      ++count;
    }
  }
  destRegion = { destIndex, destSize };
}

/** \class ExtractImageFilterRegionCopier
 * \brief A special variation of ImageRegionCopier for when the output image
 *        has fewer dimensions than the input image.
 *
 *  ExtractImageFilterRegionCopier is a special variation on ImageRegionCopier.
 *  The difference in this version is when the T1 > T2.  In this case, the
 *  output image has fewer dimension than the input image.  This only works correctly
 *  when totalInputExtractionRegion has been set.  totalInputExtractionRegion is
 *  essentially the mapping from the srcRegion space to the DestRegionSpace.
 *  The important values in totalInputExtractionRegion are when
 *  totalInputExtractionRegion.Size is = 0 for one or more of the dimensions.
 *  These values correspond to the dimensions to collapse.  When
 *  totalInputExtractionRegion.Size[dim] = 0, then the index that we have to lock
 *  destRegion.Index[dim] = totalInputExtractionRegion.Index[dim].
 *
 *  The other two cases (T1 = T2, and T1 < T2) are identical to the implementation
 *  in ImageToImageFilterDetail.
 *
 *
 * \ingroup ITKCommon
 */
template <unsigned int T1, unsigned int T2>
class ITK_TEMPLATE_EXPORT ExtractImageFilterRegionCopier : public ImageRegionCopier<T1, T2>
{
public:
  virtual void
  operator()(ImageRegion<T1> &       destRegion,
             const ImageRegion<T2> & srcRegion,
             const ImageRegion<T1> & totalInputExtractionRegion) const
  {
    using ComparisonType = typename BinaryUnsignedIntDispatch<T1, T2>::ComparisonType;
    ExtractImageFilterCopyRegion<T1, T2>(ComparisonType(), destRegion, srcRegion, totalInputExtractionRegion);
  }

  /** Duplicate the superclass method to avoid warnings. */
  void
  operator()(ImageRegion<T1> & destRegion, const ImageRegion<T2> & srcRegion) const override
  {
    ImageRegionCopier<T1, T2>::operator()(destRegion, srcRegion);
  }
};
} // namespace itk::ImageToImageFilterDetail

#endif
